This disclosure is directed to methods for the manufacture of dihydroxy aromatic compounds and dialkyl carbonates from flame retardant-containing polycarbonate compositions, and in particular to methods of making bisphenol A and dimethyl carbonate by methanolysis of bisphenol A polycarbonate composition containing phosphorus-containing flame retardants.
Polycarbonates are useful in the manufacture of articles and components for a wide range of applications, from automotive parts to electronic appliances. However, polycarbonates are not biodegradable and can present a significant bulk waste disposal problem. Accordingly, efforts have been made to recover valuable resources from polycarbonate wastes.
Polycarbonates can depolymerize in the presence of a catalyst to generate monomers such as bisphenol A and dimethyl carbonate. However, it is challenging to depolymerize polycarbonates in wastes, particularly, post-consumer low purity wastes, since these wastes contain various chemicals in addition to polycarbonates. These various chemicals can poison the catalyst, contaminate the products, and render the process expensive and inefficient. Thus, a cost effective process that allows the recovery of high quality products from polycarbonate wastes is continuously sought.